Oil is used in numerous applications and is commonly used as a lubricant in engines. Due to the broad range of engines and operating environments, lubrication oil is available in a variety of different viscosities (formulations, weights, or grades). For example, lubrication oil could be a single viscosity oil, such as SAE 30 base oil, which has a viscosity of 30 at a set testing temperature or lubrication oil could be a multi-viscosity oil, such as 15W40, 0W30, or 10W30. With multi-viscosity oils, the first number indicates a first viscosity at a first temperature (a cold temp.) and the second number indicates the oil's second viscosity at a second temperature (a hot temp.) Multi-viscosity oils are beneficial in engine use to help handle the diverse operating environments, such as cold start.
In some devices or engine systems, lubrication oil is also used as an actuation fluid for hydraulically actuated devices. For example, because lubrication oil is a common fluid source in engine systems, it is relatively easy to employ for hydraulic “muscle” in hydraulically actuated electronically controlled unit injectors or hydraulically actuated or partially actuated valves. By using hydraulic power, actuation events can be controlled independently of the engine speed (eliminating dependency on the cam shaft) and enhance engine performance. Specifically, in unit injectors, oil is pressurized to relatively high levels and is used in conjunction with an intensifier piston to pressurize fuel to injection pressure. With valves, the pressurized oil can be used to open intake or exhaust valves.
Although lubrication oil is a preferred actuation fluid in engine systems, it does have some drawbacks. The viscosity of the oil can impact the timing of the desired actuation event which, in turn, impacts engine performance. This is most common during cold starting. Often, look up tables for each grade of oil are used within the engine's electronic control unit (ECU) to help predict and adjust for an oil's viscosity at a specific temperature. Unfortunately, the oil grade used in the engine is often not known, so choosing which look up table to use is difficult and can result in decreased engine performance. Although engine manufactures may specify a specific lubrication oil to use, many customers and service providers may use different oil varieties, requiring manufactures to design engines to account for different oil types.
The present invention is intended to address one or more of the above problems.